This is a randomized, double-blind study comparing LNK01001 to placebo in participants with moderately to severely atopic dermatitis who were candidates for systemic therapy (ie, patients with a history of inadequate response to topical treatments, those who were using a systemic treatment, or those for whom topical treatments are otherwise medically inadvisable).

The objective of this study is to evaluate the efficacy and safety of LNK01001 in adult patients with moderate to severe AD who are candidates for systemic therapy.

This study includes a 35-day screening period; a 16-week randomized, placebo-controlled treatment period (Period 1); a 36-week long-term extension period (Period 2); and a 28 to 35-day follow-up period (FU).

Participants who meet eligibility criteria will be randomized in a 2:2:1:1 ratio to four treatment groups:

Group 1: LNK01001 12 mg BID (Day 1 to Week 16)， LNK01001 12 mg BID (Week 16 and thereafter) Group 2: LNK01001 24 mg BID (Day 1 to Week 16)， LNK01001 24 mg BID (Week 16 and thereafter) Group 3: Placebo (Day 1 to Week 16)， LNK01001 12 mg BID (Week 16 and thereafter) Group 4: Placebo (Day 1 to Week 16)， LNK01001 24 mg BID (Week 16 and thereafter)

Starting at Week 4, rescue therapy is allowed if medically necessary and the following parameters are met:

At Week 4 through Week 24: subjects with < 50% reduction in EASI response at any two consecutive scheduled visits, compared to the Baseline EASI score.

After Week 24: subjects with < 50% reduction in EASI at any scheduled or unscheduled visit, compared to the Baseline EASI score.

Starting at Week 16, the use of any concomitant topical medication for atopic dermatitis can be administered per the investigator's discretion and will no longer be considered as rescue therapy for analysis.

Inclusion Criteria:

• Participants must be at least ≥18 and ≤75 years of age.
• The subject has a diagnosis of atopic dermatitis for at least 1 year.
• Meets the following disease activity criteria: BSA ≥10% of AD involvement. EASI ≥16. IGA ≥3. WI-NRS ≥4.
• Documented history of inadequate response to topical corticosteroids (TCS) or topical calcineurin inhibitor (TCI) or documented systemic treatment for AD within 6 months before Baseline Visit.

Exclusion Criteria:

• Vaccinated or exposed to a live or attenuated vaccine within the 6 weeks prior to the first dose of investigational product unable or unwilling to discontinue current atopic dermatitis treatments before the study.
• Requirement of prohibited medications during the study.
• Other active skin diseases or skin infections requiring systemic treatment or would interfere with appropriate assessment of atopic dermatitis lesions.
• History of malignancy or current diagnosis of malignancy before screening visit.

In the opinion of the investigator or sponsor, any uncontrolled clinically significant laboratory abnormality that would affect the interpretation of study data or the subject's participation in the study uncontrolled diabetes, hypertension, kidney disease, liver disease, or severe heart disease.